<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        *{margin:0;padding:20px;transition:background 0.8s;}
        ul{list-style:none;background:hsl(193,66%,85%);}
        li{background:hsl(193,66%,95%);}
        .highlight{background:red;}
    </style>
</head>
<body>
    <div id="app">
        <ul @click="callback($event)">
            <li @click="callback($event)">One</li>
            <ul @click="callback($event)">
                <li @click="callback($event)">Two</li>
                <ul @click="callback($event)">
                    <li @click="callback($event)">Three. Click Me!!!</li>
                </ul>
            </ul>
        </ul>
    </div>
    
    <script src="https://cdn.jsdelivr.net/npm/vue@2.5.16/dist/vue.js"></script>
    <script>
        var pause = 200;
        var vm = new Vue({
            el:'#app',
            methods:{
                callback(event){
                    var ms = event.timeout = (event.timeout + pause) || 0;
                    var target = event.currentTarget;
                    //console.log(target);
                    setTimeout(function(){
                        target.classList.add('highlight');
                        setTimeout(function(){
                            target.classList.remove('highlight');
                        },pause);
                    },ms);
                }
            }
        });
    </script>
</body>
</html>